DIGEST 2006 - Sabita

More documents

Recommendations

Info

compositional fractions (See Table 4). Each fraction is then analysed for its contribution to the overall mix volumetrics. By comparing the size of particles that fit into the voids between the largest aggregate pieces, and the size of the largest aggregate pieces found in a fraction, ratios can be developed that are an indication of how well all the particles in the fraction fit together and what the mix characteristics will be like. The Bailey Method can be used to predict how changes in the factors that affect packing will change the resultant volumetrics, compactability and segregation potential of a particular mixture. See Table 3 for packing factors, which vary from mix to mix. • Principle 2: Evaluates the coarse fraction and how the particle sizes in the coarse fraction pack together, and how this influences the packing of the fine fraction. (The volume of voids in the coarse aggregate, course fraction compactability and segregation susceptibility are also appraised.); • Principle 3: Evaluates the packing of the overall fine fraction in the combined blend; • Principle 4: Evaluates the packing of the fine part of the fine fraction. All four principles of the Bailey Method are interactive and must be monitored for changes. If a Gradings Continuously graded Gap graded Compactive effort Type = static, impact, shearing Amount = field vs laboratory Strength Individual aggregate toughness Shape Flat and elongated Cubical or round Surface texture Smooth Rough Size Nominated max. particle size Table 3: Properties that influence mix packing and end compaction Principles of the Bailey Method: Four principles are adopted in the method: • Principle 1: Determines the break between coarse and fine aggregates. From this it is established which particles create voids and which ones fill them and which fraction (coarse or fine) is in control; gradation changes, then all four principals must be reviewed. Evaluation of Dolerite and Quartzite mixes with Bailey Method: The dolerite and quartzite mixes were evaluated with the four Bailey principles, and the results are given in Table 4. The dolerite mix, somewhere between coarse and fine (more 107
coarse) graded, may be problematic as far as the Bailey Method is concerned, as the coarse and fine fractions could be struggling for control of the volumetric properties. The CA Ratio used is slightly higher than the upper acceptable limit suggested, which could indicate possible compaction problems in the field. The FA c ratio is within the acceptable limits, but the FA f ratio is slightly higher than the suggested upper limit which would indicate high mortar stiffness (as intended in the design for deformation resistance in the fundamental design methodology . This is contradictory to the PRADO analysis of the mix, which indicates a tender mix. Large quantities of this mix have been paved in Gauteng with no significant compaction problems (including various ORTIA applications over last three years). The quartzite mix is “coarse-graded” and the coarse aggregate is therefore in control of the volumetric properties. The CA ratio is higher than the upper acceptable limit suggested, which could indicate possible compaction problems in the field. The FA c ratio is within the acceptable limits, but the FA f ratio is higher than the suggested upper limit, which would indicate high mortar stiffness (as intended in the design to ensure good rut resistance). This is in agreement with the Ratio Principle Dolerite Quartzite Acceptable range CA Ratio 1 92.7 97.5
Page 1 and 2:
DIGEST 2006
Page 3 and 4:
Mission Sabita’s plans and action
Page 5 and 6:
4. Innovation The use of steel slag
Page 7 and 8:
1 Valediction
Page 9 and 10:
economic growth. In addition to str
Page 11 and 12:
one of the world leading trade orga
Page 13 and 14:
Choosing road surfaces: Bitumen, gr
Page 15 and 16:
we can economically test a possible
Page 17 and 18:
oads. These considerations influenc
Page 19 and 20:
double that for two-lane surfaced r
Page 21 and 22:
elative fluctuation by increasing o
Page 24 and 25:
Optimising resource utilisation: Ag
Page 26 and 27:
COSHEC in 2007: Health and safety i
Page 28 and 29:
designed to assist road authorities
Page 30 and 31:
• Obtain endorsement and commitme
Page 32 and 33:
• institution of Sabita safety tr
Page 34 and 35:
Towards an informed industry: Updat
Page 36 and 37:
versions of some of Sabita’s earl
Page 38 and 39:
from texture treatments to overlays
Page 40 and 41:
South Africa's education system: A
Page 42 and 43:
environment and red tape on small a
Page 44 and 45:
Figure 2. Matric result trends the
Page 46 and 47:
professional work, within the conte
Page 48 and 49:
Assessing Teachers are often unclea
Page 50 and 51: 3 HG learners in a class of 40 SG).
Page 52 and 53: The following observations may be m
Page 54: documented successful maths and sci
Page 57 and 58: public awareness programme to illus
Page 59 and 60: Surge in SAT's knowledge transfer a
Page 61 and 62: organisation. With the improvement
Page 63 and 64: accomplished through self-study. Th
Page 65 and 66: 4 Innovation
Page 67 and 68: calcium oxide is not fully hydrated
Page 69 and 70: oad construction. As mentioned prev
Page 71 and 72: M ix type Coars e continuous Coarse
Page 73: Conclusions From the results presen
Page 76 and 77: itumen emulsion or foamed bitumen,
Page 78 and 79: operations, as well as to advance a
Page 81 and 82: Fischer-Tropsch wax bitumen modifie
Page 83 and 84: Viscosity The significant influence
Page 85 and 86: Figure 3: Layer temperature profile
Page 87 and 88: easily formed and shaped where nece
Page 89 and 90: Achieving cost-efficiency through t
Page 91 and 92: Graded stone seals The seals that a
Page 93: Figure 6 illustrates how the stone
Page 96 and 97: decided rather to use the old TRH8
Page 98 and 99: ecommendations (R69/97 for bitumino
Page 102 and 103: PRADO analysis. Large quantities of
Page 104 and 105: HMA research programme: Forensic in
Page 106 and 107: Conclusions The following conclusio
Page 108 and 109: test programme, will seek to develo
Page 111 and 112: Out of the box thoughts on traditio
Page 113 and 114: Or more appropriately, a lone thar
Page 115 and 116: seal, and everybody's happy! Or wer
Page 118 and 119: The status quo on landfill sites: D
Page 120: In August 2004 a status quo report
Page 123 and 124: Bond coats Bond coats were first us
Page 125 and 126: peak value of 1,2 J/cm 2 . Typical
Page 127 and 128: promote the breaking of the emulsio
Page 130 and 131: Bitumen stabilised materials: A per
Page 132 and 133: Figure 2: DSR testing at comparativ
Page 135 and 136: Revision of Technical Guideline 1 (
Page 137: º introducing upper limits on some
Page 140 and 141: void loss due to embedment and aggr
Page 142 and 143: Alternatives to coal tar products:
Page 144 and 145: you don’t measure” might have b
Page 146 and 147: gradually increased from approximat
Page 148 and 149: Conclusions MC 30 cutback bitumen
Page 151 and 152:
Towards industry self-regulation: T
Page 153 and 154:
Figure 2: Accidents involving heavy
Page 155 and 156:
RTMS standards for transport operat
Page 157 and 158:
operators as part of their quality
Page 159 and 160:
• System installation i.e. applic
Page 161 and 162:
Notes 169
Page 163 and 164:
Advertiser Index Advertiser Page Co
Page 165 and 166:
Sabita Video Training Aids Video se
Page 167 and 168:
Associate Members Africon Engineeri
show all

DIGEST 2006 - Sabita

Create successful ePaper yourself

Delete template?

Save as template?